GB1306040A - - Google Patents

Abstract

1306040 Determining co-ordinates of a curve electrically INSTRONICS Ltd 27 July 1971 [27 July 1970] 35298/71 Heading G1N Apparatus for determining the co-ordinates of the points on a curve on a sheet of paper comprises means for fixing the sheet under a rectangular frame 25, Fig.2, carrying perpendicular wires 41, 43 attached over pulleys 81, 83, 87, 89 to cables 49, 69, and a pick-up coil 27, Fig.6, which is manually made to follow the curve. The wires 41, 43 are fed with 90 degrees dispaced voltages from an oscillator 105 and the signals picked up by coil 27, after phase detection, represents the displacements between coil 27 and each of the wires 41, 43. These signals are fed to servomotors 101, 103 which move the wires 41, 43 individually until their cross-over point is directly under coil 27 and therefore coincides with a point on the curve. The X and Y coordinates of this point are sensed by encoders 131, 133 also driven by motors 101, 103 and recorded when a foot lever is operated. In a modification, the functions of coil 27 and wires 41, 43 are reversed, i.e. coil 27 is fed with A.C. and the signals picked up by wires 41, 43 are used to energize the servomotors.